US5305161A - Adaptive track seeking for disk drives - Google Patents

Adaptive track seeking for disk drives Download PDF

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Publication number
US5305161A
US5305161A US07/980,308 US98030892A US5305161A US 5305161 A US5305161 A US 5305161A US 98030892 A US98030892 A US 98030892A US 5305161 A US5305161 A US 5305161A
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United States
Prior art keywords
seek
microprocessor
velocity
actuator
velocity profile
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Expired - Fee Related
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US07/980,308
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English (en)
Inventor
Matthew F. Giovanetti
Kenneth F. Veseskis
Fernando A. Zayas
Bernardo Rub
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Maxtor Corp
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Digital Equipment Corp
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Assigned to DIGITAL EQUIPMENT CORPORATION reassignment DIGITAL EQUIPMENT CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GIOVANETTI, MATTHEW F., RUB, BERNARDO, VESEKIS, KENNETH F., ZAYAS, FERNADO A.
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Publication of US5305161A publication Critical patent/US5305161A/en
Assigned to QUANTUM CORPORATION reassignment QUANTUM CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DIGITAL EQUIPMENT CORPORATION
Assigned to CANADIAN IMPERIAL BANK OF COMMERCE, AS ADMINISTRATIVE AGENT reassignment CANADIAN IMPERIAL BANK OF COMMERCE, AS ADMINISTRATIVE AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: QUANTUM CORPORATION
Assigned to CANADIAN IMPERIAL BANK, AS ADMINISTRATIVE AGENT reassignment CANADIAN IMPERIAL BANK, AS ADMINISTRATIVE AGENT RELEASE Assignors: QUANTUM CORPORATION
Assigned to MAXTOR CORPORATION reassignment MAXTOR CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: QUANTUM CORPORATION
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B21/00—Head arrangements not specific to the method of recording or reproducing
    • G11B21/02—Driving or moving of heads
    • G11B21/08—Track changing or selecting during transducing operation
    • G11B21/081—Access to indexed tracks or parts of continuous track
    • G11B21/083—Access to indexed tracks or parts of continuous track on discs

Definitions

  • the present invention relates to track seeking operations for disc drives, and more particularly to methods and apparatus for controlling the track seeking servo system for a disc drive to provide optimal acquisition times for track seeking operations.
  • the servo system that controls the actuator must closely monitor and control the velocity of the head on a real time basis.
  • the position information is derived from the read signal from the head.
  • the analog read signal from the head is converted to a digital read signal by an analog to digital (A/D) converter.
  • A/D analog to digital
  • embedded servo position information in the read signal is periodically sampled and passed to a microprocessor.
  • the microprocessor calculates the measured velocity V m by taking the difference between the position indicated by the current sample and the position indicated by the previous sample and dividing the difference by the sample period.
  • the microprocessor generates an acceleration command that is used to correct any difference between the measured velocity of the head V m and a desired velocity of the head V d according to a seek velocity profile that is appropriate given the number of tracks left to travel to the destination track.
  • the microprocessor command is converted to a constant current analog control signal by a digital to analog converter. This control signal drives the actuator and thereby corrects the velocity of the head.
  • the seek velocity profile that is used by the microprocessor to determine what level of current to command to the actuator is implemented with the process of comparing the present track position of the head with the selected track position and selecting the desired velocity V d based upon this difference in tracks.
  • the microprocessor has a table of desired velocities based upon the difference in tracks for this purpose.
  • the table of desired velocities V d that are stored in the microprocessor are generally based upon empirical evaluation of a sample of disc drives operating under worst case conditions with substandard actuator motors. As a result, drives with greater seek performance potential operating under normal conditions are not able to seek any faster than weak drives operating under unfavorable conditions.
  • the present invention optimizes the track seeking operation of disc drives by adaptively changing the seek velocity profile in response to the actual performance of the drive during track seeking operations based upon the amount of head overshoot, the actuator power dissipation and the actual seek time.
  • the number of head overshoots and the actuator motor power level are monitored during periodic consecutive intervals, and the seek velocity profile is optimized only when the combination of power level and number of overshoots do not meet specified conditions.
  • FIG. 1 is a block diagram of a track seeking servo system suitable for incorporating the present invention.
  • FIG. 2 is a graphical representation of a typical seek velocity profile for a given measured velocity V m of a disc drive head, indicating desired velocities V d as a function of the number of tracks for the head to go to the desired track.
  • FIG. 3 is a typical seek velocity profile and a corresponding shifted-time seek velocity profile.
  • FIG. 4 is a flow chart of the methodology of the present invention.
  • FIG. 1 is a block diagram of a typical track seeking servo system 2.
  • the track seeking system 2 comprises an analog to digital (A/D) converter 4, a sampler 6, a microprocessor 8, a digital to analog converter 10 and an actuator motor 12.
  • A/D analog to digital
  • the input of the A/D converter 4 receives an analog read signal on a line 14.
  • the analog read signal is produced by a controlled head (not shown) that is coupled to a servo controlled actuator (not shown).
  • the A/D converter 4 converts the analog read signal to a digital read signal on a line 16.
  • the digital position information in the digital read signal is sampled by the sampler 6 on a periodic basis.
  • the sampler 6 provides position samples on a line 18 that are received by the microprocessor 8.
  • the microprocessor 8 determines the measured velocity of the head V m by comparing the positions of consecutive samples and dividing the difference in positions by the sample period. The respective positions are conveniently determined by identifying the track number information in the samples.
  • the microprocessor 8 determines the proper constant current acceleration command that is appropriate for the head to be displaced from its current position to the selected track.
  • the acceleration command is transmitted from the microprocessor 8 to the D/A converter on a line 20.
  • the D/A converter converts the acceleration command signal from the microprocessor 8 to a respective constant current signal that drives the actuator motor 12 via a line 22.
  • the microprocessor bases its determination of the appropriate constant current acceleration command for a given sample on the current measured head velocity V m , the present position of the head and the desired position of the selected track.
  • the present and desired positions of the head are conveniently compared in terms of the respective track numbers.
  • the microprocessor 8 determines a desired velocity of the head V d based upon a seek velocity profile.
  • the seek velocity profile is a lookup table of desired velocities V d as a function of the number of tracks to the destination track.
  • the constant current acceleration command issued by the microprocessor 8 for each sample period is proportional to the difference between the desired velocity V d , as determined by the seek velocity table based upon the number of tracks to go, and the measured velocity V m .
  • FIG. 2 is a graphical representation of a typical seek velocity profile for a given current measured velocity V m .
  • a line 24 represents the amplitude of the desired velocity V d as a function of the number of tracks to go to the destination track.
  • the microprocessor 8 determines the maximum attainable terminal velocity for the head V t .
  • the microprocessor 8 determines the distance, in the number of tracks, traveled in going from the terminal velocity V t to the final velocity V o at the point of the destination track x o .
  • the microprocessor 8 generates a seek velocity profile table by determining the appropriate desired velocities V d between the terminal velocity V t and the final velocity V o .
  • the terminal velocity of the head is established by the microprocessor 8 according to the following procedure.
  • the microprocessor 8 determines the distance of the longest seek for the system 2, in number of tracks.
  • the microprocessor 8 creates a generally step-shaped velocity profile over the distance of the longest seek with the terminal velocity V t set at to the maximum allowable value as determined by the drive system.
  • the terminal velocity V t is positioned along the profile for a distance of roughly half of the total distance of the seek.
  • the final values of velocities are set to the final velocity V o .
  • the terminal velocity profile so established by the microprocessor 8 is then used to determine the terminal velocity for one seek that is roughly equal to this distance.
  • the microprocessor 8 measures the terminal velocity of the seek, while using the terminal velocity profile, at a distance of roughly half the actual total length of the seek. Because of the mass moved by the actuator motor 12, the terminal velocity profile as measured is generally triangular in shape.
  • the deceleration distance going from the terminal velocity V t to the final velocity V o is then established by the microprocessor 8 according to the following procedure.
  • the microprocessor 8 determines a terminal velocity V t using the velocity profile for V t as described above with a seek length corresponding to a distance that is somewhat shorter than the distance of the seek itself to guarantee that the terminal velocity V t is reached. This is considered a "long seek".
  • the distance to go, in the number of tracks, is then measured by the microprocessor 8 from the terminal velocity V t to the final velocity V o . This is the deceleration distance for the seek.
  • the microprocessor 8 then creates an idealized seek velocity profile, based upon the relationship that the actual velocity desired at any point is proportional to the square root of the distance plus a constant. This may be expressed according to the relationship
  • the microprocessor 8 generates values of desired velocities V d for each track for the number of tracks to go for the entire distance of the seek.
  • a seek velocity profile is then created by the microprocessor 8 with the value of the desired velocity V d as a function of the number of tracks to go to the destination track.
  • the values of the idealized velocity profile so determined are applicable to a full-deceleration seek.
  • the servo system 2 does not integrate out the constant error between the desired velocity V d and the measured velocity V m because of the sampling nature of the servo system 2.
  • the microprocessor 8 shifts the seek velocity profile by the duration of one sample period.
  • the time t for each value of desired velocity V d in the idealized seek velocity profile is determined using the corresponding distance x according to the relationship ##EQU1##
  • FIG. 3 is a graphical representation of an idealized seek velocity profile and a corresponding time-shifted velocity profile.
  • a line 26 represents the amplitude of the desired velocity V d as a function of the number of tracks to go to the destination track.
  • a line represents the amplitude of the time-shifted desired velocity V d ' as a function of the number of tracks to go to the destination track.
  • the microprocessor 8 determines when such periodic updates are necessary by keeping track of its constant current command signal to monitor power dissipation of the actuator motor 12 and the number of seek overshoots to determine how well the seek velocity profile is optimized.
  • FIG. 4 is a flow chart of the procedure used by the microprocessor 8 in determining when a periodic seek velocity profile is necessary. On a periodic basis, according to a periodic interval that depends upon the individual characteristics of the drive, the microprocessor 8 makes a determination of an update.
  • the microprocessor 8 monitors a timer that is set to expire a predetermined period after each update. If the timer has expired, the microprocessor 8 recalculates the velocity seek profile. If the timer has not expired, the microprocessor 8 measures the power dissipation of the actuator motor 12 and the number of overshoots of the head for the interval.
  • the microprocessor 8 compares the power P dissipated in the interval with the maximum power P m allowed per interval and the number of overshoots OV in the interval with the maximum number of overshoots OV m allowed per interval.
  • the microprocessor 8 If P is less than P m and OV is less than OV m , the microprocessor 8 increases the value of the terminal velocity V t accordingly. If not, then the microprocessor 8 determines if P is less than P m and OV is greater than OV m . If these two conditions are true, the microprocessor 8 optimizes the seek velocity profile.
  • the microprocessor 8 determines if P equals P m and OV is less than OV m . If so, the microprocessor 8 does not perform an update during this interval. If not, the microprocessor 8 determines if P equals P m and OV is greater than OV m . If so, then the microprocessor 8 optimizes the seek velocity profile.
  • the microprocessor 8 determines if P is greater than Pm and OV is less than OV m . If so, the microprocessor 8 decreases the value of the terminal velocity V t accordingly. If not, the microprocessor 8 determines if P is greater than P m and OV is greater than OV m . If true, the microprocessor 8 optimizes the seek velocity profile. If not, the microprocessor 8 does not perform an update during this interval.
  • the present invention monitors the power for the actuator motor 12 and the number of overshoots of the head during seeks during consecutive periodic intervals and updates the seek velocity profiles for the disc drive to adaptively optimize the seek times for the disc drive under actual operation conditions.

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  • Moving Of Head For Track Selection And Changing (AREA)
US07/980,308 1990-06-29 1992-11-23 Adaptive track seeking for disk drives Expired - Fee Related US5305161A (en)

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US54635590A 1990-06-29 1990-06-29
US07/980,308 US5305161A (en) 1990-06-29 1992-11-23 Adaptive track seeking for disk drives

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US (1) US5305161A (de)
EP (1) EP0464992B1 (de)
JP (1) JPH04229467A (de)
CA (1) CA2041866A1 (de)
DE (1) DE69121327T2 (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5497360A (en) * 1993-03-24 1996-03-05 Kabushiki Kaisha Toshiba Optical disc apparatus with accessing using only reference velocity during acceleration and reference and moving velocities during deceleration
US5566148A (en) * 1993-12-27 1996-10-15 Kabushiki Kaisha Toshiba Optical disk tracking system for searching a target track based on a table of compensation reference velocity
US5684653A (en) * 1996-01-16 1997-11-04 Hewlett-Packard Company Method and apparatus for minimizing seek time in a disk drive by increasing power amplifier power based on power amplifier voltage head room
US5793558A (en) * 1996-06-05 1998-08-11 Western Digital Corporation Method for seek time optimization employing voice-coil motor current saturation level to define an adaptive deceleration profile
US5880902A (en) * 1996-04-09 1999-03-09 International Business Machines Corporation Method and apparatus for adaptively calibrating disk drive performance based on real time performance monitoring
US6115205A (en) * 1994-03-11 2000-09-05 Seagate Technology, Inc. Method for adapting seeks of a disc drive transducer to the maximum actuator current available to accelerate and decelerate the transducer
US6212027B1 (en) 1997-01-28 2001-04-03 Samsung Electronics Co., Ltd. Stable unlatch control of hard disk drive
US6442705B1 (en) * 1999-04-26 2002-08-27 International Business Machines Corporation Method of and apparatus for improving data integrity in a disk drive system
US20020135924A1 (en) * 2001-03-21 2002-09-26 Seagate Technology Llc Multi-phase acceleration of a data storage disc

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100648747B1 (ko) 1999-04-21 2006-11-23 시게이트 테크놀로지 엘엘씨 디스크 드라이브의 자체 조정 모델 기준 컨트롤러

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JPS57164476A (en) * 1981-04-02 1982-10-09 Mitsubishi Electric Corp Servo positioning mechanism of magnetic disk device
US4591933A (en) * 1983-11-28 1986-05-27 Computer Memories, Incorporated Disk drive head positioner with optimized seek operation
US4622604A (en) * 1983-05-23 1986-11-11 Kabushiki Kaisha Toshiba Magnetic head controlling apparatus
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JPS6464178A (en) * 1987-09-03 1989-03-10 Fujitsu Ltd Automatic adjusting device for magnetic disk device tester
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JPS6464178A (en) * 1987-09-03 1989-03-10 Fujitsu Ltd Automatic adjusting device for magnetic disk device tester
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5497360A (en) * 1993-03-24 1996-03-05 Kabushiki Kaisha Toshiba Optical disc apparatus with accessing using only reference velocity during acceleration and reference and moving velocities during deceleration
US5566148A (en) * 1993-12-27 1996-10-15 Kabushiki Kaisha Toshiba Optical disk tracking system for searching a target track based on a table of compensation reference velocity
US6115205A (en) * 1994-03-11 2000-09-05 Seagate Technology, Inc. Method for adapting seeks of a disc drive transducer to the maximum actuator current available to accelerate and decelerate the transducer
US5684653A (en) * 1996-01-16 1997-11-04 Hewlett-Packard Company Method and apparatus for minimizing seek time in a disk drive by increasing power amplifier power based on power amplifier voltage head room
US5880902A (en) * 1996-04-09 1999-03-09 International Business Machines Corporation Method and apparatus for adaptively calibrating disk drive performance based on real time performance monitoring
US5793558A (en) * 1996-06-05 1998-08-11 Western Digital Corporation Method for seek time optimization employing voice-coil motor current saturation level to define an adaptive deceleration profile
US6212027B1 (en) 1997-01-28 2001-04-03 Samsung Electronics Co., Ltd. Stable unlatch control of hard disk drive
US6442705B1 (en) * 1999-04-26 2002-08-27 International Business Machines Corporation Method of and apparatus for improving data integrity in a disk drive system
US20020135924A1 (en) * 2001-03-21 2002-09-26 Seagate Technology Llc Multi-phase acceleration of a data storage disc
US7158328B2 (en) * 2001-03-21 2007-01-02 Seagate Technology Llc Multi-phase acceleration of a data storage disc

Also Published As

Publication number Publication date
EP0464992A1 (de) 1992-01-08
JPH04229467A (ja) 1992-08-18
DE69121327T2 (de) 1997-02-06
EP0464992B1 (de) 1996-08-14
CA2041866A1 (en) 1991-12-30
DE69121327D1 (de) 1996-09-19

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